I would like to replace my sofa back cushion filling which is currently made of feathers/down and I think contributing to my allergies. Bamboo looks like a good alternative since it's also machine washable but I am having trouble finding it in bulk and also estimating how much I need. I found Ingeo/corn filling at Joann but am not sure how eco-friendly it is. I've tried wool pillows in the past but it gets compressed. Any help would be appreciated :)

Shredded natural latex would be the least compressable, I think. Kapok may be another option - feels more like down.

I really have no idea who would let you buy just filling - most of the organic bed places have pillows with some sort of alternate fillings - since so many of those places make their own stuff, maybe you could get them to make pillow inserts to size?